ObserverList::HasObserver now takes a const pointer.

chrome/browser/sync/backend_migrator.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_BACKEND_MIGRATOR_H_
 #define CHROME_BROWSER_SYNC_BACKEND_MIGRATOR_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
@@ skipping 40 matching lines @@
                   syncer::UserShare* user_share,
                   ProfileSyncService* service,
                   sync_driver::DataTypeManager* manager,
                   const base::Closure &migration_done_callback);
   virtual ~BackendMigrator();
 
   // Starts a sequence of events that will disable and reenable |types|.
   void MigrateTypes(syncer::ModelTypeSet types);
 
   void AddMigrationObserver(MigrationObserver* observer);
-  bool HasMigrationObserver(MigrationObserver* observer) const;
+  bool HasMigrationObserver(const MigrationObserver* observer) const;
   void RemoveMigrationObserver(MigrationObserver* observer);
 
   State state() const;
 
   // Called from ProfileSyncService to notify us of configure done.
   // Note: We receive these notificiations only when our state is not IDLE.
   void OnConfigureDone(
       const sync_driver::DataTypeManager::ConfigureResult& result);
 
   // Returns the types that are currently pending migration (if any).
@@ skipping 29 matching lines @@
   base::Closure migration_done_callback_;
 
   base::WeakPtrFactory<BackendMigrator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BackendMigrator);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_BACKEND_MIGRATOR_H_